From: Phil Sutter Date: Tue, 30 Aug 2016 17:39:52 +0000 (+0200) Subject: evaluate: Avoid undefined behaviour in concat_subtype_id() X-Git-Tag: v0.7~89 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=83e52f7a7f5eaa893e146d23ff2e9292179f9485;p=thirdparty%2Fnftables.git evaluate: Avoid undefined behaviour in concat_subtype_id() For the left side of a concat expression, dtype is NULL and therefore off is 0. In that case the code expects to get a datatype of TYPE_INVALID, but this is fragile as the output of concat_subtype_id() is undefined for n > 32 / TYPE_BITS. To fix this, call datatype_lookup() directly passing the expected TYPE_INVALID as argument if off is 0. Signed-off-by: Phil Sutter Signed-off-by: Pablo Neira Ayuso --- diff --git a/src/evaluate.c b/src/evaluate.c index 194a0349..c1ee6b19 100644 --- a/src/evaluate.c +++ b/src/evaluate.c @@ -962,7 +962,10 @@ static int expr_evaluate_concat(struct eval_ctx *ctx, struct expr **expr) "expressions", i->dtype->name); - tmp = concat_subtype_lookup(type, --off); + if (dtype == NULL) + tmp = datatype_lookup(TYPE_INVALID); + else + tmp = concat_subtype_lookup(type, --off); expr_set_context(&ctx->ectx, tmp, tmp->size); if (list_member_evaluate(ctx, &i) < 0)